Recently, due to changes in people's lifestyles (e.g., an increase in lipid intake in dietary life, an increase in drinking and smoking, and a lack of exercise), so-called life-style related diseases, such as diabetes mellitus, hyperlipemia, hypertension, and gout, which are caused by, for example, accumulation of fat or stress and reduction in liver function, have been rapidly increased, resulting in social problems. As these diseases progress, they result in complications and proceed to diseases ranked among the highest causes of deaths, such as cardiac disease and apoplexy. The latest investigation shows that hypertension is the highest risk factor in the life-style related diseases. Many antihypertensive drugs (e.g., a β blocker, an α blocker, a Ca antagonist or an ACE inhibitor) have been developed.
However, serious side effects have been reported, for example, heart failure and intraventricular block in the case of the β blocker, fainting and dizziness in the case of the α blocker, liver damage in the case of the Ca antagonist, and renal failure in the case of the ACE inhibitor (Non Patent Literature 1). Further, as for these therapeutic drugs, it is difficult to control the blood pressure of potential hypertensive patients, i.e., patients with mild hypertension (e.g., patients with high-normal blood pressure having a maximal blood pressure of 130 to 139/a minimal blood pressure of 85 to 89). Accordingly, there is a need to develop a useful pharmaceutical formulation with less side effects for patients with mild hypertension.
Meanwhile, garlic has been used not only as a food but also for the treatment of various diseases since ancient times. A characteristic component of garlic is γ-glutamyl-S-allylcysteine. When garlic is cut, crushed, grated or aged, the component is converted into water-soluble S allylcysteine (hereinafter abbreviated as “SAC”) by an enzyme called as γ-glutamyl transpeptidase contained in garlic. Another water soluble compounds which are generated by the above enzymatic reaction include S-methylcysteine and S-1-propenylcysteine, for example, in addition to SAC (Non Patent Literature 2).
It is reported that SAC has many pharmacological effects such as a preventive effect on liver damage (Non Patent Literature 3 and Patent Literature 2) and a preventive effect on colon cancer (Non Patent Literature 4). It is also reported that S-methylcysteine has a preventive effect on liver damage (Patent Literature 2) and an ameliorating effect on brain disease (Patent Literature 1).
However, it has been known that S-1-propenylcysteine has an antihypertensive effect.